Influence of ambient air pollution on global DNA methylation in healthy adults: A seasonal follow-up

Background: DNA methylation changes are potential pathways of environmentally induced health effects. We investigated whether exposure to ambient concentrations of NO2, PM10, PM2.5 and O-3 and traffic parameters were associated with global DNA methylation in blood of healthy adults. Methods: 48 non-smoking adults (25 males) with a median age of 39 years were sampled in winter and summer. Global DNA methylation in whole blood (% 5-methyl-2'-deoxycytidine, %5mdC) was analyzed with HPLC. Exposure to air pollutants at the home address was assessed using interpolated NO2, PM10, PM2.5 and O-3 concentrations for various exposure windows (60- to 1-day moving average exposures and yearly averages) and GIS-based traffic parameters. Associations between pollutants and %5mdC were tested with multiple mixed effects regression models. Results: Average %5mdC (SD) was 4.30 (0.08) in winter and 4.29 (0.08) in summer. Men had higher %5mdC compared to women both in winter (4.32 vs. 4.26) and summer (431 vs. 4.27). When winter and summer data were analyzed together, various NO2, PM10 and PM2.5 moving average exposures were associated with changes in %5mdC (95% CI) ranging from -0.04 (-0.09 to 0.00) to -0.14 (-0.28 to 0.00) per IQR increase in pollutant. NO2, PM10, PM2.5 and 03 moving average exposures were associated with decreased %5mdC (95% Cl) varying between -0.01 (-0.03 to 0.00) and -0.17 (-0.27 to -0.06) per IQR increase in pollutant in summer but not in winter. Conclusion: Decreased global DNA methylation in whole blood was associated with exposure to NO2, PM,,,, PM2.5 and O-3 at the home addresses of non- adults. Most effects were observed for the 5- to 30-day moving average exposures. (C) 2013 Elsevier Ltd. All rights reserved.